Acridombs



Patented Dec. 27, 1949 UNITED STAT-E #92392 MESSFMMGANTBBAQUINONE- HansLecher, meld,

anfil ar n :Eorste Someryille, N. 3., jgsignors'ftoikmerican (JyanamidNew York, "N. Y., a corporation NODI'W plica-tion ,Mayl, 19.45,

wherein the pair of carbon atoms 61C elongs to an anthraquinone nucleusand the pair of carbon atoms C364 belongs to any aromatic ring Theanthraquinone 'acridone may be tmsubstituted or one or other of therings may carry substituents such as alkyl, aryl, halogen, etc., whichgroups are not affected by thereagent used in the ring closure. Some ofthe anthraquinone acridones have *only one 'a'nthraquinorre acridonering and others may have two or more.

Anthraquinone aoridones have been prepared fromorthocarboxysubstitutedarylanrino anthraquinones in which the 'carboxygroup maybe attached to the anthraquinone :nucleus or to the otheraromatic ring. .Dhese compounds may be considered to have .zone or other:of the iollowing essential groups:

t a o coo in which the .carbon atoms :01 to Eahanezthe'same significanceas in the group xeferredzto ashore;

In the past the anthraquinone iacridones have been prepared by ringclosure using-3mm ring closing reagents, such as {sulfuric mid, 5111--furyl chloride, chlorosulfonic acid, acetic panhadride,benzoyl-chloride; also thionyilichloridaalcne and phosphorus oxychloridealone :have been used. While it has been possible ,to produce theanthraquinone ,acridones bythe ring-closure pro-r cedures of the prior.art these processeshaue J sented serious disadvantages whichhzwe theirgeneralapplicability. ,In general there are four principal types ofdisadvanta es. one ,or more of which have been encountered in mama ualcases. They are .as follows:

*1. .In the firstplace, when phosphorus ,ozgychloride "used, theacridone is contaminated amorphous, sticky decomposition products of socomm. (Cl. ace -21s) phosphorus oxyc'liloride which makes it tojhaud le,particularly in filtration, thus mailmg fu the p o s n e p ns 2. flow yild. whi n mo n to fis cost. because .the carboxy arylaminoanthraquinones ns da reasen sa e p s e chem ca s- .8. Unsat f o Pu ty wi h s a se u taster in m n .cases a e cridone a e r dual nsedas dsstufis .or inter ed a s dyes iifis- Impurities often ha e s r ous e e onshad or rain: prop rtie and o en is c en isto be noted even when thamoun I imp t es is small. 4 s. lS de reactions, o 'examp e. deca ox lti nstead of dehydra on with rin s11 e.s1t 0na .ti n mensul ur a is u et Zlihe present invention is based on .a two process in which the firststep is to heat the carbox aryi mino anth aquinones with th nyl chloride.to moderatelyelevated temperatures, for example, ,of the order ofmagnitude of about C.,, which ,converts the carboxy .arylaminoanthraquinone -into its acid chloride without material ring closure.Then the-acid chloride, preferably,

though not necessarily, without isolation, isfheated with small amountsof phosphorous oxychloride, usuallyin catalytic amounts, the temperaturebeing somewhat higher and being maintained at a sufliciently Highpointto produce ring closure.

fllhe amount of thionyl chloride .to' be used in the first step shouldbe atleast stoichiometrical, best results being obtained with a slight,excess, for example, 10.150 15% The exact amount of ,thiqnyl chlorideis not critical. It is preferred to carry out the first step of thepresent process in a solvent, preferably an organic liquid, which issubstantia l inert .to the action of thionyl chloride and phosphorusoxychloride. A wide choice of solvents are available, but it ispreferred to ,use one in which the anthraquinone acridone to be producedis appreciably soluble at the boiling point of the solventandsubstantially iosofluble or of very flowsolubllity at lowertemperatures. Ifypi'cal cheap and satisfactory solvents arenitrobenzene, dichlorbenzene and trichlorbenzene. solv nts poss s ruisit inertness to thionyl chloride and hosphorus oxyclilorideand theright -solubi1ity for the anthraq none ,acridones'a't boiling and lowertemperatures. {they alsmhavebo'fling points which are suitable for thelast step of ringclosure, which can thereforejbe efiected under reflux,providing an automatic temperawre c ntrol. The process is not in any way'to these three solvents ,and other inert liquids may be used, providedthey have a reasonably elevated boiling point. Where the boiling pointis above the temperature at which it is desired to ring close, theadditional advantage of automatic temperature control by operation undera reflux is not enjoyed, and with such liquids the process whileeflicient, requires somewhat more careful supervision as it lacks theautomatic temperature control.

excellent results and permit using a cheaper product which is readilyavailable.

reagents constitutes a practical operating advan-- tage.

The amount of phosphorus oxychloride is not I Of course it must bepresent in sufiicient critical.

The relative insensitiveness of the process to the purity of theconditions andthe wide range of choice makes step are well above thetemperatures used in the first step but are in no sense critical. Ringclosure begins somewhat below 150 C. and is quite satisfactory at 150C., which is high enough to efiect the ring closure and to removehydrogen chloride andexcess thionyl {chloride Higher temperatures may beused; thus, for example,

.refluxing at 210 C., the boiling point of nitro- High purity of eitherthe thionyl chloride or the phosphorus oxychloride is not necessary.Theordinary commercial grades of these reagents give I b'enzene does notintroduce any deleterious effect.

'fact, this-refluxing at a higher temperature 'presents advantages witha number of the acrid ones in that, it produces a more readilyfilterable product on slowcooling. The fact that the temperature'of thesecond step is in no sense critical permits adjustment to meet thedesired working f-the process both simple and flexible.

amounts to exert its catalytic ring closing effect:

phosphorus oxychloride. The lower limit of phosphorus oxychloride setout above represents a practical limit. There is no sudden break, butbelow this amount of phosphorus oxychloride the yields crop 01f and theprocess becomes uneconomical. For best results it is desirable tooperate somewhat above the minimum and larger amounts of phosphorusoxychloride do not adversely affect the emciency of the ring closingstep. However, no advantages in speed of reaction or increase in yieldare obtained by exceeding .25 mols of phosphorus oxychloride. Largeramounts are without benefit and merely represent a waste of theoxychloride.

It is a further advantage of the present invention that the orthocarboxyarylamino anthrafects the efliciency of the process. However,-

small amounts up to a maximum of 10% do not interfere appreciably withthe yield. It is therefore unnecessary to employ an elaboratepurification process in obtaining the orthocarboxy arylaminoanthraquinone to be used in the process. This reduces the cost of theraw material and represents a further economical advantage.

As has been stated above the temperature in the first step is of theorder of magnitude of about 100 C. Best results are obtained slightlyunder this temperature, the preferred range being from 80 to 95 C. Thetemperature is not critical and extremely elaborate temperature controlswith their accompanying high cost are not necessary. Of course thetemperature should not be allowed to vary within wide limits, andtheordinary good chemical practice of maintaining reasonable temperaturecontrol should be followed.

It is unnecessary to isolate the acid chloride of the orthocarboxyarylamino anthraquinone produced by the first step of the presentprocess. In'fact, it is preferable not to isolate it because the sameinert solvent in which the first step is preferably carried out forms avery satisfactory reaction medium for the second step. The fact that itis not necessary to isolate the product of the first step of the processis an important operating advantage as it is unnecessary to remove thereaction medium from the vessel in which the first step was carried out.The second or ring closure step is effected by raising the temperatureand adding the catalytic amounts of phosphorus oxychloride. Thetemperatures for the second constitute at least one factor.

' The acridone produced is usually in a crystalline;form. Normally itfilters readily and foreign matter may be removed by washing withadditional small quantities of cold solvent. The high efficiency. of thepresent process, which with many acridones results in yields in excessof produces a' reaction mixture which is not containinated with largeamounts of impurities. In case the acridone is tobe subjected to further-chemical processing, for example, if it is desired to chlorinate theproduct, the further processing may be effected in the reaction mixturewithout isolation of the acridone. This represents a saving in time,handling, and solvent loss, and represents a great practical advantage.

It is not intended to restrict the present invention to any theory ofaction. It seems probable, though, that the following explanation mayThionyl chloride is efiicient in producing acid chlorides, but not.very' efiicient in ring closure. Phosphorus oxychloride ring closesprimarily by dehydration and then forms sticky viscous decompositionproducts. In the present process the first step converts the carboxylicgroup into the acid chloride and ring closure in the second step is thenaccompanied byelimination of hydrogen chloride rather than water.Phosphorus oxychloride appears to be even more efficient in eliminatinghydrogen chloride than in eliminating water, which is rather surprising,as it is normally considered as acting primarily-as a dehydrating agentand not as a Friedel-Crafts catalyst. Unquestionably the phosphorusoxychloride does not act as a straight dehydrator or even a hydrogenchloride acceptor. The small-amounts which give excellent results arefar too little to act as a reagent in combining with hydrogen chloride,and therefore it seems probable that phosphorus oxychloride is able toremove hydrogen chloride and effect ring closure by a catalytic actionwhich is entirely different from its usual dehydrating action whichrequires stoichiometrical quantities.

The process of the present invention should not be confused with aprocess in which a mixture of phosphorus oxychloride and thionylchloride are used. Such a mixture will not behave in the same manner asthe two step process of the present invention in which each of the tworeagents is used alone in a separate step. When a mixture is used thesame difllculties are encountered with the formation of viscous stickydecomposition products of phosphorus oxychloride.

The improved two step process of the present invention is applicable tothe production of large number of anthraquinone'acridones. One of theimportant groups includes the anthraquinone.

2;1-.benzacridone, the parent member ofwhich hasthe following formula:

Various substituents may be present on one or M both rings, typicalderivatives being the following: 4-methy1-, 5-methyl-, 4',6'-dimethyl-,5'- phenyl-, 5-fluoro-, 4'- or 6-trifluoromethyl--, 4-, 3'-,' 4'-, 5-,or 6'-chloro-, 5,8-, 3,4'-, 3f,6-, 4",5-, 4=,6-, 5,6-dichloro-,3,4',6'-, 4,3',5'-, 4,4,6'-, 3,4',5'-, 3',4',6-, 3,5,6-,4',5',6'-trich10ro-', 3,3',5,6-, 3,4,5,6'-, 4,3',4',5'-, 4,3',5,6'-,4,4',5',6" 3,4',5',6'-tetrachloro-, 3,3',4',5',6"-,4,3',4',5',6-pentachloro, 3-bromo-, 5-bromo- 3',5'-dibromo-, 6-nitr0-,4-, 5-, 8- or 5-amino-, 4hydroxy-, 4 or 5'-methoxy-, 3'-phenoxy-, 3.-methy1-6'-chloro-, 3,3,5'-trichloro-4-amino-, 4'-trifiuoromethyl-i-amino, 3-ch1oro-4-amino-, 6"- chloro-4-amino-,3,3,5'-trichloro-4-amino-, 6" chloro 3' methoxy-, 6' chloro-3'-ethoxy-,3'- ch1oro-3-phenoxy-, 4',6-dichloro 3' phenoxyanthraquinone-2,1 (N)-benzacridone.

The isomeric anthraquinone-2,3-benzacridone is another type of ringwhich may be prepared by the present invention. Similarly anthraquinonedibenzacridones, anthraquinone naplrthacridones, anthraquinonedinaphthacridones, anthraquinone dibenzacridone naphthaorldoneanthrimide acridones (diphthaloyl acridones) and the like are alsoincluded.

The C3 and C4 carbon atoms of the chain type formula may also belong toanother type of nucleus, for example, anthrathrone, anthracene,benzanthrone, meso benzidanthrone, dibenzop'yrene-quinone,naphthacene-quinone and pyrene. As in the case of anthraquinone-2,1-benzacridone these other compounds may have substituents, such as alkyl,aryl, halogen, nitro, amino, alkylamino, arylamino, acylamino, hydroxy,alkoxy and aryloxy.

The following are a few formulas of typical unsubstituted anthraquinoneacridones which can be prepared by the process of the present invention.

Anthraquinone-benzacridones (phthaloyl acridones)Anthnquindnedibenficridone mhthacridone A thrimide acridone (piphthnloylacridonel) The invention will be illustrated-in de- 15 8tailinconjunction with the following specific examples which aretypical. The parts are by weight.

Example 1 25' parts of l-(o-carboxyanilino) anthraquinone are slurriedin approximately 90 parts of nitrobenzene. 9.8 parts of thionyl chlorideare slowly added while stirring and heating at 'C. This temperature ismaintained for a proximately three hours. Then 1.7 parts of phosphorusoxychloride are added, together with additional amounts of nitrobenzeneto the now thickened slurry. The mixture is slowly brought to refluxwith th evolution of much hydrogen chloride accompanying the rise intemperature. The acridone is obtained by allowing the solution to cooland crystallize, filtering, washing with cold nitrobenzene and finallysteam stripping. The yield of anthraquinone-2,l (N) -benzacridone isabout of theory.

The yield of 95% obtained above may be compared with the yields whichare obtainable with thionyl chloride or phosphorus oxychloride when usedalone. Thus, when the same amount of thion'yl chloride is used under thesame temperature conditions the yield is only 71%. Similarly, whenphosphorus oxychloride is used in stoichiometrical amounts and themixture heated first at 190--200 C. and then for some hours at 150- 160,C. the yield is 70%. This represents about the maximum yields obtainablewhen either reagent is used alone in a single step process. In the caseof the product obtained with phosphorus cxychloride alone the reactionmass is very stickyv and filters with great difiiculty and thisrepresents a much less satisfactory physical form. in addition to thedecreased yield.

Example 2 co co The reaction mixture from Example 1, without isolatingthe acridone, is subjected to chlorination byheating at about 8090 C.for 2-3 hours with 1.6 parts of iodine and 22 parts of sulfurylchloride, together with sufilcient nitrobenzene to enable thoroughstirring. The temperature is then slowly increased to to C. and thattemperature maintained for approximately one 70 hour longer. The mixtureis allowed to cool slowly without stirring and the resulting redcrystalline mass filtered, washed with nitrobenzene, and the solventremoved. A chlorinated anthraquinone-2,1 (N) -benzacridone havingsuperior dyeing properties is obtained in excellent yields.

- Er mple .98 parts .of orthodichlorobenzene and parts of 1 9 (ocarboxyanilino) anthraquinone are mixed with stirring and 9.8 parts ofthionyl chloridezare slowly added. The mixture is heated to 80-90 C. andheld at that temperature with stirring for approximately three hours.Then 1.7 parts of phosphorus oxychloride are added, together withadditional amounts of ortho-dichlombenzene .to the now thickened slurry.The mixture is slowly brought to reflux; a stron evolution of hydrogenchloride takes place. The product is obtained by allowing the solutionto crystallize out on slowcooling, filtering, washing with coldorthodichlorobenzene, and finally steaming. The yield ofanthraq-uinone-2,1 (N) -benzacridone is excellent.

Emmple 4 15 parts of 1-anilino-2-carboxy-anthraquinone are mixed in 90parts of nitrobenzene and 5.9 parts of thionyl chloride are slowlyadded. The mixture is then heated and stirred at 80-90 C. forapproximately three hours. 0.8 part of phosphorus oxychloride is thenadded and the mixture is slowly heated to reflux accompanied by theevolution of hydrogen chloride- The dark red solution isallowed to cooland to crystallize, and the crystals are separated from nitrobenzene byfiltration and steam stripping. An excellent yield of anthraquinone-2,1(N) -benzacridone is obtained.

Example 5 CO c0 color.

60 parts of 1,5-di(carboxyanilino) anthraquinone are slurried in 480parts of nitrobenzene. To the slurry held at 75 to C. are added slowly35 parts of thionyl chloride and the stirring and heating are continuedfor two hours at 75 to 80. 7 parts of phosphorus oxychloride are thenadded and the mixture is stirred at 145 to 150 C. for 1 to 2 hours andthen at reflux temperatures for approximately /2 hour longer. When cool,the crystalline mass is filtered, washed with nitrobenzene, and freedfrom the solvent by steam stripping. The anthraquinone-2,l (N) -6,5 (N)-dibenzacridone is Obtained in a very pure state and in exc llent yields.

Example 6 25 parts of. l-(fl-naphthylamino) -2-carboxyanthraquinone areslurried in 120 parts of nitrobenzene towhich 9.8 parts of thionylchloride are added. The mixture is heated and stirred for 2 .to 3 hours.at to C. 1.7 parts .of

'. phosphorus oxychloride and 60 parts of nitrobenzene are then addedand the slurry is slowly heated to the reflux temperature and held atreflux for approximately /2 hour. After cooling the crystalline mass isfiltered, washed with nitrobenzene and freed from solvent by steamstripping. The yield of anthraquinone-2,l (N), 1',2 (N) -naphthacridoneis obtained in excellent yields.

Example 7 9.5 parts of 5-nitro-1,1'-dianthraquinonylamine- 2'-carboxylicacid, parts of nitrobenzene and 5.5 parts of thionyl chloride arestirred, heated up to a temperature of about l80 C. and kept there untilacid chloride formation is complete. 0.65 part of phosphorus oxychlorideis then added and the mass is stirred further at -l90 for 2 hours. Aftercooling to 100, the nitrobenzeneis steamed out, and the insolublereaction product digested for an hour with a mixture of 100 parts water,100 parts alcohol and 2 parts caustic soda. The product is then filteredand washed free of alkali. The reddish brown dyestufi having the abovestructure is obtained in good yields. It gives a brown-violet vat anddissolves in conc. sulfuric acid with an orange Example 8 NH CO 10.4parts of -benzoylamino-1,1-dianthraquinonylamine-2'-carboxylic acid areintroduced into 120 parts of nitrobenzene, 3.0 parts of thionyl chlorideare added, and the mass is stirred at about 110-120 for 3 hours, andthen for an additional hour at 140-145. After cooling to about 100, 0.65part of phosphorus oxychloride and 30 parts of nitrobenzene are addedand the mixture is heated again to 150 and held at that temperature withstirring for 3 hours. After cooling to room temperature, the product isfiltered, washed with nitrobenzene and alcohol, and slurried in amixture of 150 parts water, 100 parts alcohol and 2 parts sodiumhydroxide at the boiling ternperature for 1 hour. It is then filtered,washed with water and dried. If desirable, the product may be aftertreated with benzoyl chloride. The yield is excellent. It dissolves inconcentrated sulfuric acid with an orange color and dyes cotton redshades from a brown-violet vat.

We claim:

1. A process for producing an anthraquinone acridone from a compoundcontaining at least one structural unit of the following formula:

wherein the pair of carbon atoms C1 and C2 belong to an anthraquinonenucleus and the pair of carbon atoms C3 and C4 belong to any aromaticnucleus, and wherein one X stands for COOH and the other X stands for H,which comprises converting said compound into its acid chloride byheating in an inert organic solvent with at least one mol of thionylchloride per molecular equivalent of carboxylic acid group, and thenheating the resulting acid chloride at a higher temperature withphosphorus oxychlo- 12 ride in amounts of at least 0.05 mol ofphosphorus oxychloride per molecular equivalent of carboxylic acidgroup.

2. A process according to claim 1 in which the carbon atoms 0304 arepart of an unfused benzene ring.

3. A process according to claim 1 in which the carbon atoms C304 arepart of a naphthalene ring.

4. A method of producing anthraquinone-2,1- benzacridone from1(o-carb0xylanilino)-anthraquinone which comprises converting the lattercompound into its acid chloride by heating it in an inert organicsolvent with at least one mol of thionyl chloride per molecularequivalent of carboxylic acid group, and then heating the resulting acidchloride at a higher temperature with phosphorus oxychloride in anamount of at least 0.05 mol per mol of carboxyanilino anthraquinone.

5. A method of producing anthraquinone-2,1 (N) 6,5 (N) -dibenzacridonefrom 1,5 di(carboxylanilino -anthraquinone which comprises convertingthe latter compound into its acid chloride by heating it in an inertorganic solvent with at least one mol of thionyl chloride per molecularequivalent of carboxylic acid group,

' and then heating the resulting acid chloride at a higher temperaturewith phosphorus oxychloride in an amount of at least 0.1 mol per mol ofcarboxyanilino anthraquinone.

6. A method of producing anthraquinone-2,1 (N), 1',2' (N)-naphthacridone from l-(p-naphthylamino) -2-carboxyanthraquinone whichcomprises converting the latter compound into its acid chloride byheating it in an inert organic solvent with at least one mol of thionylchloride per molecular equivalent of carboxylic acid group, and thenheating the resulting acid chloride at higher temperature withphosphorus oxychloride in an amount of at least 0.05 mol per mol ofcarboxy naphthylamino anthraquinone.

HANS Z. LECHER. WARREN S. FORSTER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 961,048 Ullmann June 7, 19102,042,165 Wuertz May 26-, 1936 2,374,891 Peter May 1, 1945

